Underwater pressure vessels are designed to withstand the hydrostatic pressure exerted on the vessels by the surrounding water. Additional loads may include impact or underwater explosions. Any combination of loads that exceeds the design capability of the vessel may cause the vessel structure to fail. If a pressure vessel is not completely filled, then volumes exist that can collapse suddenly (implode). If an underwater vessel implodes in close proximity to other vessels such as submarines, adverse effects to systems or structures may occur.
When a pressure vessel implodes in water, a potentially significant pressure wave results. This wave has an initial underpressure phase that is followed by a shock-like overpressure phase. The underpressure results from the collapse of the structural boundary, exposing the internal volume (typically low air pressure inside the structure) to the ambient water pressure. The shock-like overpressure results from the collision of the surrounding water and structure against the vessel. As the structure collapses, the surrounding water builds momentum as it rushes inward during the collapse. When the air volume reaches a minimum, the velocity of the water is forcibly arrested and the water compresses, resulting in a shock wave that travels back out into the water. Damage to nearby vessels may result. The prior art does not teach underwater vessels that are designed to mitigate implosion loads.